Toner feed means for a developer station of a printer or a photocopier

ABSTRACT

A pneumatic toner feed mechanism for a developer station of a printer or copier is disclosed. The feed mechanism includes at least two storage containers which are separately allocated to the developer chambers of the developer station. The toner storage containers act as intermediate storage units which are linked to the developer chambers of the developer station by supply ducts. Toner is supplied from bottle-shaped transport containers by a vacuum transport mechanism to the toner storage containers. The transport mechanism includes controllable solenoid valves. The toner level is detected by way of a control mechanism that preferably includes associated capacitive sensors. When a level of toner in a storage container exceeds a predetermined level, the associated valves are opened thereby eliminating the vacuum and associated automatic toner refill. A controller or control means may include a priority control system which preferably refills the toner of the main printing color.

FIELD OF THE INVENTION

The present invention relates generally to printers and copiers and,more specifically, to toner delivery mechanisms for printers andcopiers. Still more specifically, the present invention relates to tonerdelivery mechanisms for printers and copiers having a plurality ofdeveloper chambers for the separate application of toner to differentdeveloper regions arranged on an electrographic intermediate carrier.

BACKGROUND OF THE INVENTION

A toner delivery mechanism is fundamentally disclosed by EP-B1 0 332669. This is thereby a matter of a device for the pneumatic filling oftoner from a bottle-shaped transport container into a toner reservoir inwhich toner is completely suctioned from the transport container withthe assistance of underpressure and is thus conveyed into the tonerreservoir. The toner reservoir is in communication with a developerstation having only a single developer chamber. It contains a mixingmeans composed of a wire bow and a metering drum of cellular materialarranged in the connecting region to the developer station via whichtoner, which is dosed in printing mode, is supplied to the developerstation dependent on its filling level. The toner reservoir itself isdivided via a filter into a suction space and a settling space, wherebythe settling space is connected to the toner bottle via a hose and thesuction space is coupled to an underpressure blower.

Further, WO 94/27193 discloses an electrographic printer means withwhich it is possible to print a band-shaped recording medium multi-colorin simplex and duplex mode. To this end, the printer means contains aplurality of separate developer stations arranged successively orside-by-side that separately ink developer regions on an electrographicintermediate carrier (photoconductor) that are allocated to thedeveloper stations.

In multi-color simplex mode, what is referred to as spot color mode, aprint image is first transfer-printed onto the recording medium with afirst color, the print image is then fixed, and the recording medium isthen returned to the transfer printing station and a print image isprinted with a second color and subsequently fixed in a second passthrough the fixing station. The transfer printing station is thustraversed with a single recording medium in two recording medium websarranged parallel next to one another. Corresponding developer regionson the photoconductor are allocated to the recording medium webs. Sincephotoconductors, whether bands or drums, cannot be arbitrarily wide, itis necessary to arrange the developer regions side-by-side on thephotoconductor without significant spacing. The appertaining developerstations must thus also be arranged in close proximity next to oneanother. To this end, it has already been proposed to employ a singledeveloper station with a plurality of separate developer chambers inwhich differently colored toner, for example red toner and black toner,is respectively contained.

When toner from a standard toner reservoir with a predetermined capacityis delivered to the developer chambers, then large-volume containers areneeded for maintaining the printing operation. These require much spaceand can therefore not be employed in conjunction with a developerstation having a plurality of developer chambers. When smallercontainers are employed, this shortens the printing operation.

It has turned out that the great majority of printing is in only asingle color, for example black, given multi-color printing withhigh-speed printers of said species. Only occasionally are individualareas of the print image emphasized with another color or aremulti-color graphics or images inserted. Different degrees ofconsumption of the various types of toner thus occur. The printing timeis thus limited by the capacity of the container having the toner thatis used most. When, on the other hand, the containers are made ofdifferent sizes according to the statistical use, then there is the riskthat, given a sudden, longer operation in multi-color, the differentlycolored toner components needed therefor will be prematurely used andthe printing operation will therefore be interrupted.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to fashion a toner deliverymechanism of the species initially cited such that a continuous printeroperation is assured.

In the invention, the toner reservoirs are fashioned as true bufferstorages to which toner from supply bottles (transport containers) issupplied more or less continuously dependent on their filling level. Apneumatic conveyor means with underpressure is thereby utilized. Whenthe filling level is simultaneously downwardly transgressed at aplurality of toner reservoirs, a priority circuit sees to it that thetoner component used most in the ongoing printer operation isreplenished first from the corresponding transport container and theprinter operation can thus be continued.

The toner is conveyed out of the toner bottles (transport containers)into the toner boxes (toner reservoirs) with underpressure according tothe suction principle. In order to assure an adequate suction powergiven low underpressure, extraction is carried out from only one bottlegiven a permanently adjacent underpressure at the extraction channel. Tothis end, the extraction channel is fashioned with suction clock valvessuch that a multi-path valve arises. It is thus possible to control thefilling of the toner boxes merely on the basis of selective actuation ofthe valves. The toner box with the principal printing color is filledwith priority via the priority circuit.

In an embodiment, the present invention provides a toner delivery systemfor a developer station of a printer or copier that comprises first andsecond developer chambers. The toner delivery system comprises at leasttwo toner reservoirs including a first toner reservoir and a secondtoner reservoir. The first toner reservoir being disposed in the firstdeveloper chamber; the second toner reservoir being disposed in thesecond developer chamber. The first toner reservoir includes a firststorage area which is in communication with a first toner bottlecontaining a first toner of a first color. The first storage area isalso in communication with a first suction line for drawing first tonerfrom the first toner bottle into the first storage area. The firststorage area also accommodates a first level sensor for determining thelevel of first toner in the first toner area. Analogous to the firsttoner reservoir, the second toner reservoir also includes a secondstorage area which is in communication with a second toner bottle whichcontains a second toner, of a different color than the first toner. Thesecond storage area is also in communication with a second suction linefor drawing second toner from the second toner bottle into the secondstorage area. Like the first storage area, the second storage area alsoincludes a second level sensor for determining the level of second tonerin the second storage area. The first suction line has a first valve forisolating the first suction line from the first storage area and,similarly, the second suction line has a second valve for isolating thesecond suction line from the second storage area. The first and secondvalves and the first and second level sensors are electrically coupledand controlled by a controller.

In an embodiment, when the first sensor sends a signal to the controllerindicating that the level of first toner in the first storage area islow, the controller sends an open signal to the first valve therebyestablishing communication between the first suction line and the firststorage area and causing first toner to be drawn from the first tonerbottle into the first storage area. Similarly, when the second sensorsends a signal to the controller indicating that the level of secondtoner in the second storage area is low, the controller sends an opensignal to the second valve thereby establishing communication betweenthe second suction line and the second storage area and resulting insecond toner being communicated from the second toner bottle to thesecond storage area.

In an embodiment, one of the first and second valves is closed at alltimes and the controller institutes a priority system whereby when thefirst sensor sends a signal to the controller indicating that the levelof first toner in the first storage area is low, the controller sends anopen signal to the first valve thereby establishing communicationbetween the first suction line and the first storage area regardless ofwhether a signal has been received from the second sensor indicatingthat the level of second toner is low in the second storage area. Thus,the level of toner in the first storage area takes priority over thelevel of toner in the second storage area.

In an embodiment, each reservoir comprises a filter disposed between thestorage area and a suction space. The suction space being connected to arespective suction line. The filter preventing toner from beingcommunicated from a storage area to a suction space.

In an embodiment, the first and second suction lines are connected to acommon vacuum source.

In an embodiment, the suction line supplies a constant vacuum or aconstant low pressure supply to the first and second suction spaces.

In an embodiment, the first and second valves are solenoid valves.

In an embodiment, the first and second toner reservoirs each comprise amixing element for mixing and agitating the toner in the storage areas.

In an embodiment, a partition is disposed between the first and secondtoner reservoirs and the partition accommodates bearings for the firstand second mixing elements.

In an embodiment, conveyors are disposed adjacent to each storage area.The conveyors communicating toner from the respective storage areas tothe respective developer chambers.

In an embodiment, the first and second level sensors are capacitivesensors.

Other objects and advantages of the present invention will becomeapparent from reading the following detailed description and appendedclaims, and upon reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are shown in the drawings and are describedin greater detail below with reference to the drawings, by way ofexample. In the drawings:

    ______________________________________                                        FIG. 1   a schematic sectional view of a developer station with                                      toner reservoirs arranged thereon;                     FIG. 2          a schematic illustration of a toner box with two toner                               reservoirs A and B;                                    FIG. 3          a schematic illustration of the toner delivery to the                                toner reservoir A;                                     FIG. 4          a schematic illustration of the toner delivery to the                                toner reservoir B;                                     FIG. 5          a schematic illustration for explaining the position of                              the illustrations employed;                            FIG. 6          a schematic illustration of the view W of FIG. 5;             FIG. 7          a schematic illustration of the view Y of FIG. 5;             FIG. 8          a schematic illustration of the view X of FIG. 5;             FIG. 9          a schematic illustration of the view Z of FIG. 5;             FIGS. 10-11                                                                            a schematic illustration for explaining the functions of                                   the closures; and                                       FIG. 12        a schematic illustration of the sealed bearing in the                                region of the partition between neighboring                      transport                                                                                  containers.                                             ______________________________________                                    

It should be understood that the drawings are not necessarily to scaleand that the embodiments are sometimes illustrated by graphic symbols,phantom lines, diagrammatic representations and fragmentary views. Incertain instances, details which are not necessary for an understandingof the present invention or which render other details difficult toperceive may have been omitted. It should be understood, of course, thatthe invention is not necessarily limited to the particular embodimentsillustrated herein.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

An electrophotographic printer device for the multi-color printing ofband-shaped recording media in simplex and duplex mode, as disclosed byWO 94/27193, contains a developer station with appertaining toner box astoner buffer storage that is described in greater detail below withreference to the Figures. The developer station is fundamentallycomposed of two developer stations arranged in a single housing,separated by a thin partition and coupled to one another via thepartition that respectively fundamentally have the functional structuredisclosed by WO 94/03842. The function of the drums participating in thedeveloping process and their technical characterization is described inWO 94/03842. In this respect, this publication is a constituent part ofthe present disclosure and is herein incorporated by reference.

The developer station shown in FIG. 1 with appertaining toner boxcontains a housing G that is arranged in the device and can be pulledout via rails and that has two developer chambers E that are separatedvia a partition ZW. Two developer drums W1 and W2 composed of arotatable hollow drum with magnet stator arranged therein as well as ofa dosing drum DW of plexiglass with illumination means arranged thereinare respectively arranged in the developer chambers E. A transport drumTW seated in the developer sump under the developer drums transports thedeveloper mix to the developer drums W1 and W2. A single carrier capturedrum FFW spanning the developer chambers E is arranged outside thedeveloper chambers E in the exit region of the developer station, thiscarrier capture drum FFW being constructed analogous to the developerdrums. All drums except the transport drum are grouped around aphotoconductor drum FT according to the course of the developer gap.They rotate in the illustrated arrow directions. They are driven incommon via a gearing arranged laterally at the housing G of thedeveloper station.

A toner box TBO (shown in FIGS. 1 and 2) with toner reservoirs A and Brespectively allocated to the developer chambers E that are coupled withthe developer chambers E via delivery channels ZK is arranged above thedeveloper chambers E. Via a filter F, each toner reservoir A and B issubdivided into a settling space AR and a suction space SR (FIGS.10,11).

The settling space AR contains a mixing means M in the form of a wirebow 11 seated on a mixer shaft 10 and a conveyor means FE in the form ofa dosing drum 12 of cellular material that transports toner to thedeveloper chambers E. Mixer shaft 10 with wire bow 11 seated thereon andthe dosing drum 12 are driven via a gearing with chain drive 13 andelectric motors 14 (FIGS. 6 and 7) that is laterally arranged at thetoner reservoirs A and B. Each toner reservoir A and B thereby has aseparate drive.

A capacitative sensor 15/1, 15/2 as filling level sensor for acquiringthe filling level of the toner is located in every settling space AR ofevery toner reservoir A and B.

The toner reservoir A accepting a first toner of a first color and thetoner reservoir B accepting a second toner of a second color aremirror-symmetrically constructed; together, they form the toner box TBO.In the regions of their sidewalls 16, the toner reservoirs A, B arepositively connected to one another releasable via screws. The drives13, 14 for the mixing means M and the conveyor means FE are respectivelylocated in the region of their other sidewalls 17. Mixing means M andthe conveyor means FE are respectively seated in the sidewalls 16, 17.

The partition of the sidewalls 16 arranged in the boundary regionbetween neighboring toner reservoirs A, B contains the rolling bearings18 shown in FIG. 12 for the mixing means m and the conveyor means FE,whereby the rolling bearings 18 are sealed from the settling spaces ARof the toner reservoirs A, B by seals 19 (shaft seals). Toner reservoirTB and developer station E are electrically conductively connected toone another but are insulated from the apparatus accepting the housingsince toner reservoir TBO and developer station E lie at a bias voltagecompared to the photoconductor drum FT during printer operation. Allelectrical and mechanical component parts of the toner box TBO having aconnection to the apparatus must therefore be constructed electricallyinsulated.

As can be particularly seen from FIG. 2 in combination with theschematic illustrations of FIGS. 10 and 11, each settling space AR ofthe toner reservoirs A and B is connected via a delivery line 20/1 and20/2 to a toner transport container TA, TB in the form of a tonerbottle. The toner container TA thereby contains toner of a first color,for example black; the toner container TB contains toner of a secondcolor, for example red. Each suction space SR of the toner reservoirs Aor B can in turn be coupled via a closure in the form of a suction clockvalve VA, VB to an extraction channel 21 to which a means in the form ofa blower generating an underpressure is flanged. The valves VA and VBare fashioned as solenoids with a valve piston 22 that, when undercurrent, opens an admission opening 23 to the extraction channel 21 and,when not under current, closes the admission opening 23 via a springelement. It is thus assured that all admission openings 23 are closedgiven an outage of the current. The valves VA and VB are allocated tothe respective toner reservoirs A and B. Underpressure is constantlyadjacent at the extraction channel 21 during printer operation. Theallocated valve VA or VB is opened so that the corresponding toner fromthe toner bottles TA or TB can then be supplied to the correspondingsettling spaces AR of the toner reservoirs A or B. The respectivelyother valve VB, VA thereby remains closed. With the assistance of theapplied underpressure, the toner from the supply bottles TA, TB thusproceeds into the settling spaces AR and is intercepted there via thefilter F. This filter F prevents a passage of the toner into the suctionspaces SR. The alternating switching of the valves VA and VB isnecessary so that adequate underpressure is always available fortransporting the toner. It is thus possible even given slightunderpressure to see to a corresponding, reliable transport of the tonerfrom the toner supply bottles TA, TB to the settling spaces AR of thetoner reservoirs A and B. Both valves VA and VB can be closed duringactual printing operation, so that the underpressure has no negativeinfluence on the toner transport to the developer chambers of thedeveloper station.

For toner delivery of, for example, black toner from the transportcontainer TA into the toner reservoir A of the toner box TBO, the valveVA is placed under current according to the illustration of FIG. 3 and,thus, the admission opening 23 is opened. The valve VB is withoutcurrent and the appertaining admission opening 23 is thus closed.Toner-air mixture thus proceeds from the toner transport container TAvia the delivery line 20/1 into the settling space AR of the tonerreservoir A. The toner settles in the settling space AR, and thetransport air proceeds via an intermediate channel 24 arranged in thesidewalls 26 and 17 through the admission opening 23 at the valve VAinto the extraction channel 21 to the underpressure blower. For thetransport of, for example, red toner from the toner transport containerTB into the toner reservoir B, the valve VA is closed according to FIG.4 and the valve VB is opened by being placed under current. Toner-airmixture thus proceeds from the toner transport container TB via thedelivery channel 20/2 into the settling space AR of the toner reservoirB via a through channel 25 of the toner reservoir A. The red tonersettles in the settling space AR therein. The extraction air proceedsvia an opening 26 of the sidewall 17 of the toner reservoir B into achannel 27 to the valve VB with its admission opening 23 and proceedsfrom the latter to the blower of the means generating the underpressurevia the central extraction channel 21 or suction line conducted throughthe toner reservoirs A and B.

The delivery of the toner from the toner bottles TA and TB into thecorresponding toner reservoirs A and B is controlled via amicroprocessor-controlled control means C (FIG. 2) that is in turncoupled, on the one hand, to the capacitative sensors 15/1 and 15/2 ofthe toner reservoirs A and B and, on the other hand, to the valves VAand VB. Via the capacitative sensors 15/1 and 15/2, the controller Cthereby acquires the filling level of the toner in the settling spacesAR of the toner reservoirs A and B. When the toner supply drops below aprescribable level, the controller C opens the corresponding valves VAor VB of the toner reservoirs A and B, as a result whereof tonerautomatically proceeds into the appertaining settling spaces AR. So thatit is assured that continued printer operation is assured given apotential, simultaneous downward transgression of the toner level inboth toner reservoirs A and B, the main printing color, for exampleblack, of the currently ongoing printing operation is replenished withpriority. To this end, the control means C is coupled to a prioritycontrol GS. This priority control is in communication with or is acomponent part of the device controller (not shown here). It acquiresthe ongoing operating condition of the printer device, i.e. printingwith the currently running main color, for example black, namely inthat, for example, the data stream of the characters to be printed isacquired in the image memory and evaluated. In the form of a signal, ittransmits this operating condition to the control C that thenprioritizes the filling of the toner reservoir A (black toner color) orthe filling of the toner reservoir B (red toner color) in a standardelectronic way, namely in that it opens the appertaining valve VA or VBpriority-dependent. The priority can also be designationally input inadvance when, for example, printing in black is to be assured.

The inventive toner delivery mechanism for a two-color developer stationof a printer or copier device was described above on the basis of atoner box TBO that is composed of two mirror-symmetrically arrangedtoner reservoirs A and B that are correspondingly allocated to thedeveloper chambers of the developer station. When, for example infull-color operation, a developer station is to be supplied that, forexample, contains three or four developer chambers with differentlycolored toner components, then a corresponding plurality of tonerreservoirs can be analogously arranged, these being controlled viacorresponding valves. Each printing color can thus be used in equivalentfashion as main color, i.e. full color printing is possible with allcolors together. The amount of toner supply is thereby determined onlyby the size of the external toner supply bottles.

The described, divided toner box of FIG. 2, moreover, can be easilymounted on the developer station E. To this end and according to theillustration of FIGS. 1 and 9, the entire toner box is put in place ontothe developer station and is thereby mechanically centered via centeringelements. In the region of a plug strip 28, the electrical components ofthe toner box TBO are thereby automatically connected to a cooperatingplug 28/1 of the developer station. A circumferential seal 29 seals theplacement region or, respectively, the delivery channels ZK to thedeveloper station. In order to be able to clean or, respectively,replace the filter F in the suction space SR, the toner reservoirs A orB are covered in detachable fashion by a cover 30 secured via screws.

From the above description, it is apparent that the objects of thepresent invention have been achieved. While only certain embodimentshave been set forth, alternative embodiments and various modificationswill be apparent from the above description to those skilled in the art.These and other alternatives are considered equivalents and within thespirit and scope of the present invention.

We claim:
 1. A toner delivery system for a developer station of aprinter or copier device that comprises a first and second developerchambers, the toner delivery system comprising:at least two tonerreservoirs including a first toner reservoir and a second tonerreservoir,the first toner reservoir being disposed in the firstdeveloper chamber, the second toner reservoir being disposed in thesecond developer chamber, the first toner reservoir comprising a firststorage area, the first storage area being in communication with a firsttoner bottle containing a first toner, the first storage area also beingin communication with a first suction line for drawing first toner fromthe first toner bottle into the first storage area, the first storagearea also accommodating a first level sensor for determining the levelof first toner in the first storage area, the second toner reservoircomprising a second storage area, the second storage area being incommunication with a second toner bottle containing a second toner, thesecond storage area also being in communication with a second suctionline for drawing second toner from the second toner bottle into thesecond storage area, the second storage area also accommodating a secondlevel sensor for determining the level of second toner in the secondstorage area, the first suction line having a first valve for isolatingthe first suction line from the first storage area, the second suctionline having a second valve for isolating the second suction line fromthe second storage area, the first and second valves and the first andsecond level sensors being electrically coupled to a controller.
 2. Thetoner delivery system of claim 1 whereinthe first sensor sends a firsttoner low signal to the controller when the level of the first toner inthe first storage area falls below a predetermined level and thecontroller sending an open signal to the first valve upon receipt ofsaid first toner low signal from the first sensor so that first toner iscommunicated from the first toner bottle to the first storage area, andthe second sensor sends a second toner low signal to the controller whenthe level of the second toner in the second storage area falls below apredetermined level and the controller sending an open signal to thesecond valve upon receipt of said second toner low signal from thesecond sensor so that second toner is communicated from the second tonerbottle to the second storage area.
 3. The toner delivery system of claim1 whereinthe first toner reservoir further comprises a first suctionspace and a first filter disposed between the first suction space andthe first storage area, the second toner reservoir further comprises asecond suction space and a second filter disposed between the secondsuction space and the second storage area.
 4. The toner delivery systemof claim 1 wherein the first and second suction lines are connected to acommon vacuum source.
 5. The toner delivery system of claim 4 whereinthe suction line supplies a constant vacuum to the first and secondstorage areas.
 6. The toner deliver system of claim 3 wherein the firstfilter prevents migration of first toner from the first storage area tothe first suction space and the second filter prevents migration ofsecond toner from the second storage area to the second suction space.7. The toner delivery system of claim 1 wherein one of the first andsecond valves must is in a closed position at all times.
 8. The tonerdelivery system of claim 2 wherein one of the first and second valvesmust is in a closed position at all times and, in the event a firsttoner low signal and a second toner low signal is received by thecontroller during a common time period, the controller sends an opensignal to the first valve resulting in the communication of first tonerfrom the first toner bottle to the first storage area before thecontroller sends an open signal to the second valve to providecommunication of second toner from the second toner bottle to the secondstorage area.
 9. The toner delivery system of claim 1 wherein the firstand second valves are solenoid valves.
 10. The toner delivery system ofclaim 1 whereinthe first toner reservoir comprises a first mixingelement for mixing and agitating the first toner in the first storagearea, and the second toner reservoir comprises a second mixing elementfor mixing and agitating the second toner in the second storage area.11. The toner delivery system of claim 10 wherein the first and secondtoner reservoirs are disposed side-by-side with at least one partitiondisposed therebetween, the partition comprising bearings for the firstand second mixing elements.
 12. The toner delivery system of claim 1whereinthe first storage area is disposed adjacent to a first conveyorfor communicating first toner from the first storage area to one of thedeveloper chambers, and the second storage area is disposed adjacent toa second conveyor for communicating second toner from the second storagearea to another of the developer chambers.
 13. The toner delivery systemof claim 12 wherein the first and second toner reservoirs are disposedside-by-side with at least one partition disposed therebetween, thepartition comprising bearings for the first and second conveyors. 14.The toner delivery system of claim 1 wherein the first toner is of afirst color and the second toner is of a second different color.
 15. Thetoner delivery system of claim 1 wherein the first and second tonerreservoirs are disposed side-by-side with a central partition disposedtherebetween, the first and second toner reservoirs being detachablyconnected to one another.
 16. The toner delivery system of claim 1wherein the first level sensor is a capacitive sensor and the secondsensor is a capacitive sensor.
 17. A toner delivery system for adeveloper station of a printer or copier device that comprises aplurality of developer chambers at least a first developing chamber anda second developing chamber for separate application of toner to aplurality of developer regions arranged on an electrographicintermediate carrier, the toner delivery system comprising:at least twotoner reservoirs including a first toner reservoir and a second tonerreservoir, the first toner reservoir being disposed in a first developerchamber, the second toner reservoir being disposed in a second developerchamber, the first toner reservoir comprising a first storage area and afirst suction space with a first filter disposed therebetween, the firststorage area being in communication with a first toner bottle containinga first toner, the first storage area accommodating a first level sensorfor determining the level of first toner in the first storage area, thesecond toner reservoir comprising a second storage area and a secondsuction space with a second filter disposed therebetween, the secondstorage area being in communication with a second toner bottlecontaining a second toner, the second storage area accommodating asecond level sensor for determining the level of second toner in thesecond storage area, the first storage area in fluid communication witha suction line with a first valve disposed therebetween, the secondstorage area in fluid communication with the suction line with a secondvalve disposed therebetween, the first and second valves and the firstand second level sensors being electrically coupled to a controller, thefirst sensor sending a first toner low signal to the controller when thelevel of the first toner in the first storage area falls below apredetermined level and the controller sending an open signal to thefirst valve upon receipt of said first toner low signal from the firstsensor so that first toner is communicated from the first toner bottleto the first toner storage area, the second sensor sending a secondtoner low signal to the controller when the level of the second toner inthe second storage area falls below a predetermined level and thecontroller sending an open signal to the second valve upon receipt ofsaid second toner low signal from the second sensor so that second toneris communicated from the second toner bottle to the second storage area.18. The toner delivery system of claim 17 wherein one of the first andsecond valves must be in a closed position at all times and, in theevent a first toner low signal and a second toner low signal is receivedby the controller during a common time period, the controller sends anopen signal to the first valve resulting in the communication of firsttoner from the first toner bottle to the first storage area before thecontroller sends an open signal to the second valve to providecommunication of second toner from the second toner bottle to the secondstorage area.
 19. The toner delivery system of claim 17 whereinthe firsttoner reservoir comprises a first mixing element for mixing andagitating the first toner in the first storage area, the second tonerreservoir comprises a second mixing element for mixing and agitating thesecond toner in the second storage area, the first and second tonerreservoirs being disposed side-by-side with at least one partitiondisposed therebetween, the partition comprising bearings for the firstand second mixing elements.
 20. The toner delivery system of claim 17whereinthe first storage area is disposed adjacent to a first conveyorfor communicating first toner from the first storage area to one of thedeveloper chambers, the second storage area is disposed adjacent to asecond conveyor for communicating second toner from the second storagearea to another of the developer chambers, the first and second tonerreservoirs are disposed side-by-side with at least one partitiondisposed therebetween, the partition comprising bearings for the firstand second conveyors.